Backside features with intermitted pin fins

ABSTRACT

A method of manufacturing a heat shield panel including pouring melted wax into a negative pattern of the heat shield panel, the heat shield panel including first pin fins with rounded tops and second pin fins with flat tops; allowing the wax to solidify to form a positive pattern of the heat shield panel; removing the positive pattern from the negative pattern by using an ejector rod to push the positive pattern away from the negative pattern at the flat top of each of the one or more second pin fins; coating the positive pattern with a ceramic; melting the positive pattern away from the ceramic, the ceramic having a cavity forming a second negative pattern of the heat shield panel; pouring melted metal into the cavity; allowing metal in the cavity to cool to form the heat shield panel; and removing the ceramic from the heat shield panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. Non-Provisionalapplication Ser. No. 15/686,344 filed Aug. 25, 2017, issued as U.S. Pat.No. 10,619,852, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND

The subject matter disclosed herein generally relates to combustors ingas turbine engines and, more particularly, to heat shield panels incombustors of gas turbine engines.

A combustor of a gas turbine engine may be configured and required toburn fuel in a minimum volume. Such configurations may place substantialheat load on the structure of the combustor (e.g., panels, shell, etc.).Such heat loads may dictate that special consideration is given tostructures which may be configured as heat shields or panels configuredto protect the walls of the combustor. Even with such configurations,excess temperatures at various locations may occur leading to oxidation,cracking, and high thermal stresses of the heat shields or panels.Manufacturing of heat shield panels is a difficult process andimprovements to the manufacturing process are greatly desired.

SUMMARY

According to one embodiment, a heat shield panel for a combustor of agas turbine engine is provided. The heat shield comprising: a panel bodyhaving a first surface configured to be oriented toward a combustionzone of a combustor, and a second surface opposite the first surface,the second surface being configured to be oriented toward a combustorliner of the combustor; a plurality of first pin fins projecting fromthe second surface of the panel body, wherein each of the plurality offirst pin fins has a rounded top opposite the second surface; and one ormore second pin fins projecting from the second surface of the panelbody, wherein each of the one or more second pin fins has a flat topopposite the second surface.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the one or more secondpin fins are intermittently spaced amongst the plurality of first pinfins.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the one or more secondpin fins are separated from each other by about 0.5 inches (1.27centimeters).

In addition to one or more of the features described above, or as analternative, further embodiments may include that the flat top of eachof the one or more second pin fins is about parallel to the secondsurface where each of the one or more second pin fins are located.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the pluralityof first pin fins are about equal in height.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the pluralityof first pin fins have a height equal to about 0.023 inches (0.058centimeters).

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the pluralityof first pin fins further comprises a first radius located proximate thesecond surface and a second radius located proximate the rounded top,and wherein the first radius is different from the second radius.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first radius islarger than the second radius.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first radius isabout equal to 0.015 inches (0.0381 centimeters).

In addition to one or more of the features described above, or as analternative, further embodiments may include that the second radius isabout equal to 0.0125 inches (0.03175 centimeters).

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the pluralityof first pin fins further comprises a diameter, and wherein a ratio ofthe height to the diameter is about equal to 0.8.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the one ormore second pin fins further includes a radius about equal to a radiusof each of the plurality of first pin fins.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the one ormore second pin fins further includes a radius greater than a radius ofeach of the plurality of first pin fins.

In addition to one or more of the features described above, or as analternative, further embodiments may include one or more third pin finsprojecting from the second surface of the panel body, wherein each ofthe one or more third pin fins has a flat top opposite the secondsurface.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the one ormore third pin fins are located proximate one of the one or more secondpin fins.

In addition to one or more of the features described above, or as analternative, further embodiments may include connectors to connect thepanel body to the combustor liner.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the pluralityof first pin fins are cylindrical in shape.

In addition to one or more of the features described above, or as analternative, further embodiments may include that each of the one ormore second pin fins are cylindrical in shape.

According to another embodiment, a combustor for a gas turbine engine isprovided. The combustor for a gas turbine engine comprising: a combustorliner defining a combustion volume; and at least one heat shield panelcomprising: a panel body having a first surface configured to beoriented toward a combustion zone of the combustor, and a second surfaceopposite the first surface, the second surface being configured to beoriented toward the combustor liner of the combustor; a plurality offirst pin fins projecting from the second surface of the panel body,wherein each of the plurality of first pin fins has a rounded topopposite the second surface; and one or more second pin fins projectingfrom the second surface of the panel body, wherein each of the one ormore second pin fins has a flat top opposite the second surface.

According to another embodiment, a method of manufacturing a heat shieldpanel, the method comprising: pouring melted wax into a negative patternof the heat shield panel, the heat shield panel comprising: a panel bodyhaving a first surface configured to be oriented toward a combustionzone of a combustor, and a second surface opposite the first surface,the second surface being configured to be oriented toward a combustorliner of the combustor; a plurality of first pin fins projecting fromthe second surface of the panel body, wherein each of the plurality offirst pin fins has a rounded top opposite the second surface; and one ormore second pin fins projecting from the second surface of the panelbody, wherein each of the one or more second pin fins has a flat topopposite the second surface; allowing the wax to solidify to form apositive pattern of the heat shield panel; removing the positive patternfrom the negative pattern by using an ejector rod to push the positivepattern away from the negative pattern at the flat top of each of theone or more second pin fins; coating the positive pattern with aceramic; melting the positive pattern away from the ceramic, the ceramichaving a cavity forming a second negative pattern of the heat shieldpanel; pouring melted metal into the cavity; allowing metal in thecavity to cool to form the heat shield panel; and removing the ceramicfrom the heat shield panel.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, that the followingdescription and drawings are intended to be illustrative and explanatoryin nature and non-limiting.

BRIEF DESCRIPTION

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a partial cross-sectional illustration of a gas turbineengine, in accordance with an embodiment of the disclosure;

FIG. 2 is a cross-sectional illustration of a combustor, in accordancewith an embodiment of the disclosure;

FIG. 3 is an illustration of a heat shield panel, in accordance with anembodiment of the disclosure;

FIG. 4 is an illustration of a heat shield panel, in accordance with anembodiment of the disclosure;

FIG. 5 is an illustration of a heat shield panel, in accordance with anembodiment of the disclosure; and

FIG. 6 is a flow chart illustrating a method of manufacturing a heatshield panel for a combustor of a gas turbine engine, in accordance withan embodiment of the disclosure.

The detailed description explains embodiments of the present disclosure,together with advantages and features, by way of example with referenceto the drawings.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

Combustors of gas turbine engines experience elevated heat levels duringoperation. Impingement and convective cooling of panels of the combustorwall may be used to help cool the combustor. Convective cooling may beachieved by air that is trapped between the panels and a shell of thecombustor. Impingement cooling may be a process of directing relativelycool air from a location exterior to the combustor toward a back orunderside of the panels.

Thus, combustor liners and heat shields are utilized to face the hotproducts of combustion within a combustion chamber and protect theoverall combustor shell. The combustor liners may be supplied withcooling air including dilution passages which deliver a high volume ofcooling air into a hot flow path. The cooling air may be air from thecompressor of the gas turbine engine. The cooling air may impinge upon aback side of a heat shield panel that faces a combustor liner inside thecombustor. In order to increase surface area of the heat shield paneland thus also increase cooling, the back side of the heat shield panelmay include pin fins that extend away from the panel. The pin finsintroduces challenges into the manufacturing process, which is typicallydone by investment casting. The pin fins inhibit the removal for a waxmold from a negative mold of the heat shield panel. Embodimentsdisclosed herein include apparatuses and methods to aid in the removalof a wax mold from a negative mold of the heat shield panel during theinvestment casting manufacturing process.

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct, while the compressor section 24 drives air along a coreflow path C for compression and communication into the combustor section26 then expansion through the turbine section 28. Although depicted as atwo-spool turbofan gas turbine engine in the disclosed non-limitingembodiment, it should be understood that the concepts described hereinare not limited to use with two-spool turbofans as the teachings may beapplied to other types of turbine engines including three-spoolarchitectures.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided, and the location of bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure compressor 44 and a low pressureturbine 46. The inner shaft 40 is connected to the fan 42 through aspeed change mechanism, which in exemplary gas turbine engine 20 isillustrated as a geared architecture 48 to drive the fan 42 at a lowerspeed than the low speed spool 30. The high speed spool 32 includes anouter shaft 50 that interconnects a high pressure compressor 52 and highpressure turbine 54. A combustor 300 is arranged in exemplary gasturbine 20 between the high pressure compressor 52 and the high pressureturbine 54. An engine static structure 36 is arranged generally betweenthe high pressure turbine 54 and the low pressure turbine 46. The enginestatic structure 36 further supports bearing systems 38 in the turbinesection 28. The inner shaft 40 and the outer shaft 50 are concentric androtate via bearing systems 38 about the engine central longitudinal axisA which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 300, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The turbines 46, 54 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion. It will be appreciated that each of the positions of the fansection 22, compressor section 24, combustor section 26, turbine section28, and fan drive gear system 48 may be varied. For example, gear system48 may be located aft of combustor section 26 or even aft of turbinesection 28, and fan section 22 may be positioned forward or aft of thelocation of gear system 48.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10), thegeared architecture 48 is an epicyclic gear train, such as a planetarygear system or other gear system, with a gear reduction ratio of greaterthan about 2.3 and the low pressure turbine 46 has a pressure ratio thatis greater than about five. In one disclosed embodiment, the engine 20bypass ratio is greater than about ten (10:1), the fan diameter issignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 has a pressure ratio that is greater thanabout five 5:1. Low pressure turbine 46 pressure ratio is pressuremeasured prior to inlet of low pressure turbine 46 as related to thepressure at the outlet of the low pressure turbine 46 prior to anexhaust nozzle. The geared architecture 48 may be an epicycle geartrain, such as a planetary gear system or other gear system, with a gearreduction ratio of greater than about 2.3:1. It should be understood,however, that the above parameters are only exemplary of one embodimentof a geared architecture engine and that the present disclosure isapplicable to other gas turbine engines including direct driveturbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8Mach andabout 35,000 feet (10,688 meters). The flight condition of 0.8 Mach and35,000 ft (10,688 meters), with the engine at its best fuelconsumption—also known as “bucket cruise Thrust Specific FuelConsumption (‘TSFC’)”—is the industry standard parameter of lbm of fuelbeing burned divided by lbf of thrust the engine produces at thatminimum point. “Low fan pressure ratio” is the pressure ratio across thefan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The lowfan pressure ratio as disclosed herein according to one non-limitingembodiment is less than about 1.45. “Low corrected fan tip speed” is theactual fan tip speed in ft/sec divided by an industry standardtemperature correction of [(Tram ° R)/(518.7° R)]0.5. The “Low correctedfan tip speed” as disclosed herein according to one non-limitingembodiment is less than about 1150 ft/second (350.5 m/sec).

Referring now to FIG. 2 with continued reference to FIG. 1. FIG. 2illustrates a combustor section 26 of a gas turbine engine 20. As shown,a combustor 300 defines a combustion chamber 302. The combustion chamber302 includes a combustion zone 370, as shown in FIG. 2. The combustor300 includes an inlet 306 and an outlet 308 through which air may pass.The air may be supplied to the combustor 300 by a pre-diffuser 110.

As shown in FIG. 2, compressor air is supplied from a compressor section24 into an exit guide vane 112, as will be appreciated by those of skillin the art. The exit guide vane 112 is configured to direct the airflowinto the pre-diffuser 110, which then directs the airflow toward thecombustor 300. The combustor 300 and the pre-diffuser 110 are separatedby a shroud chamber 113 that contains the combustor 300 and includes aninner diameter branch 114 and an outer diameter branch 116. As airenters the shroud chamber 113 a portion of the air may flow into thecombustor inlet 306, a portion may flow into the inner diameter branch114, and a portion may flow into the outer diameter branch 116.

The air from the inner diameter branch 114 and the outer diameter branch116 may then enter the combustion chamber 302 by means of one or moreaperture 309, which may include nozzles, holes, etc. The air may thenexit the combustion chamber 302 through the combustor outlet 308. At thesame time, fuel may be supplied into the combustion chamber 302 from afuel injector 320 and a pilot nozzle 322, which may be ignited withinthe combustion chamber 302. The combustor 300 of the engine combustorsection 26 may be housed within a shroud case 124 which may define theshroud chamber 113.

The combustor 300, as shown in FIG. 2, includes multiple heat shieldpanels 400 that are mounted on an interior surface of one or morecombustion liner 330 and are arranged parallel to the combustion liner330. The combustion liner 330 can define circular or annular structureswith the heat shield panels 400 being mounted on a radially inward linerand a radially outward liner, as will be appreciated by those of skillin the art. The heat shield panels 400 can be removably mounted to thecombustion liner 330 by one or more attachment mechanisms 332. In someembodiments, the attachment mechanism 332 may be integrally formed witha respective heat shield panel 400, although other configurations arepossible. In some embodiments, the attachment mechanism 332 may be abolt or other structure that may extend from the respective heat shieldpanel 400 through the interior surface to a receiving portion oraperture of the combustion liner 330 such that the heat shield panel 400may be attached to the combustion liner 330 and held in place. The heatshield panels 400 partial enclose a combustion zone 360 within thecombustion chamber 302 of the combustor 300.

The heat shield panel 400 is composed of a panel body 402 having a firstsurface 410 and a second surface 420 opposite the first surface 410. Thefirst surface 410 is configured to be oriented toward the combustionzone 370 of the combustor 300. The second surface 420 is configured tobe oriented toward a combustor liner 330 of the combustor 300.

Referring now to FIG. 3-5 with continued reference to FIGS. 1 and 2.FIG. 3 illustrates an enlarged view of a heat shield panel 400 of thecombustor 300 of a gas turbine engine 20. As discussed above, the heatshield panel 400 is composed of a panel body 402 having a first surface410 and a second surface 420 opposite the first surface 410. The heatshield panel 400 further includes a plurality of first pin fins 430projecting from the second surface 420 of the panel body 402. Each ofthe plurality of first pin fins 430 has a rounded top 432 opposite thesecond surface 420. Each of the plurality of first pin fins may becylindrical in shape as seen in FIGS. 3-4. It is understood that each ofthe plurality of first pin fins 430 may have shapes other thancylindrical. The heat shield panel 400 also includes one or more secondpin fins 460 projecting from the second surface 420 of the panel body402. Each of the one or more second pin fins 460 has a flat top 462opposite the second surface 420. Each of the one or more second pin finsmay be cylindrical in shape as seen in FIGS. 3-4. It is understood thateach of the one or more second pin fins 460 may have shapes other thancylindrical. In an embodiment, the flat top 462 of each of the one ormore second pin fins 460 is about parallel to the second surface 420where each of the one or more second pin fins are located. It isunderstood that the second surface 420 may be curved, thus the flat top462 of each of the one or more second pin fins 460 may be parallel tothe second surface 420 where each of the one or more second pin fins 460are located. Advantageously, having the flat top 462 parallel to thesecond surface 420 allows an ejector rod to be utilized duringmanufacturing to provide a force perpendicular to the second surface 420in order to remove a wax mold away from a negative mold of the heatshield panel 400 (discussed later in relation to method 600). Aattachment mechanism 332 to connect the panel body 402 to the combustorliner 330 may be seen in FIG. 3.

As seen in FIG. 3, the one or more second pin fins 460 areintermittently spaced amongst the plurality of first pin fins 430. Theone or more second pin fins 460 may be spaced apart from each other by afirst selected distance D1. In an embodiment, the first selecteddistance D1 may be about equal to 0.5 inches (1.27 centimeters), thusthe one or more second pin fins 460 are separated from each other byabout 0.5 inches (1.27 centimeters). In an embodiment, each of the firstpin fins 430 may be equal in height H1. The height H1 is the distancemeasured from the rounded top 432 to the second surface 420, as seen inFIG. 4. In another embodiment, each of the plurality of first pin fins430 have a height H1 equal to about 0.023 inches (0.058 centimeters).The height H2 of each of the one or more second pin fins 460 may beequal to the height H1 of each of the plurality of first pin fins 430.Moreover, each of the plurality of first pin fins 430 include a firstradius R1 located proximate the second surface 420 and a second radiusR2 located proximate the rounded top 432. As seen in FIG. 4, the firstradius R1 is different from the second radius R2. The first radius maybe larger than the second radius R2. In an embodiment, the first radiusR1 is about equal to 0.015 inches (0.0381 centimeters). In anembodiment, the second radius R2 is about equal to 0.0125 inches(0.03175 centimeters). Each of the plurality of first pin fins 430include a diameter DIAL In embodiment, the diameter DIA1 may be aboutequal to 0.030. In another embodiment, a ratio (H1/DIA1) of the heightH1 to the diameter DIA1 is about equal to 0.8.

Each of the one or more second pin fins 460 may have a radius R3different than a radius R1, R2 of each of the plurality of first pinfins 430. In an embodiment, each of the one or more second pin fins 460may include a radius R3 about equal to a radius R1, R2 of each of theplurality of first pin fins 430. Whereas, in another embodiment, each ofthe one or more second pin fins 460 further includes a radius R3 greaterthan a radius R1, R2 of each of the plurality of first pin fins 430. Forexample, second pin fin 460 may take up the same area of multiple firstpin fins 430 on the second surface 420. In another embodiment, panelbody 402 may include one or more third pin fins 490 projecting from thesecond surface 420 of the panel body 402. Each of the one or more thirdpin fins 490 has a flat top 492 opposite the second surface 420. Each ofthe one or more third pin fins 490 may be located proximate one of theone or more second pin fins 460, as seen in FIG. 5. Advantageously, thethird pin fins 490 may provide points for additional leverage for anejector rod during the manufacturing process of the heat shield panel400.

Referring now to FIG. 6 with continued reference to FIGS. 1-5. FIG. 6 isa flow chart illustrating a method 600 of manufacturing a heat shieldpanel 400, according to an embodiment of the present disclosure. Atblock 602, melted wax is poured into a negative pattern of the heatshield panel 400. At block 604, the wax is allowed to solidify to form apositive pattern of the heat shield panel 400. At block 606, thepositive pattern made from wax is removed from the negative pattern byusing an ejector rod to push the positive pattern away from the negativepattern at the flat top 462 of each of the one or more second pin fins460. At block 608, the positive pattern made from wax is coated with aceramic. At block 610, the positive pattern made from wax is melted awayfrom the ceramic, thus leaving a cavity formed in the ceramic. Thecavity forming a second negative pattern of the heat shield panel 400.At block 612, melted metal is poured into the cavity within the ceramic.At block 614, metal within the cavity is allowed to cool to form theheat shield panel 400. At block 616, the ceramic is removed from theheat shield panel 400 and what remains is the full formed metallic heatshield panel 400.

While the above description has described the flow process of FIG. 6 ina particular order, it should be appreciated that unless otherwisespecifically required in the attached claims that the ordering of thesteps may be varied.

Technical effects of embodiments of the present disclosure includeutilizing pin fins with flat tops spaced intermittently amongst pin finswith round tops in order to ease the manufacturing process of a heatshield panel for a combustor of a gas turbine engine.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A method of manufacturing a heat shield panel,the method comprising: pouring melted wax into a negative pattern of theheat shield panel, the heat shield panel comprising: a panel body havinga first surface configured to be oriented toward a combustion zone of acombustor, and a second surface opposite the first surface, the secondsurface being configured to be oriented toward a combustor liner of thecombustor; a plurality of first pin fins projecting from the secondsurface of the panel body, wherein each of the plurality of first pinfins has a rounded top opposite the second surface; and one or moresecond pin fins projecting from the second surface of the panel body,wherein each of the one or more second pin fins has a flat top oppositethe second surface; allowing the wax to solidify to form a positivepattern of the heat shield panel; removing the positive pattern from thenegative pattern by using an ejector rod to push the positive patternaway from the negative pattern at the flat top of each of the one ormore second pin fins; coating the positive pattern with a ceramic;melting the positive pattern away from the ceramic, the ceramic having acavity forming a second negative pattern of the heat shield panel;pouring melted metal into the cavity; allowing metal in the cavity tocool to form the heat shield panel; and removing the ceramic from theheat shield panel.